344 



ft. 



P 



COMPARATIVE ANATOMY 



Tabvlated Resume — {Continued). 

 Anamuia. Amniota. 



The proximal portion becomes 

 in most cases (except in Cyclo- 

 stomes and Teleosts) related to 

 the testis and functional in the 

 transmission of the semen, the 

 distal functioning as a kidney. 



Persists as the kidney. 



Functions in most higher 

 Fishes merely as the urinary 

 duct. 



In Elasmobranchs, Amphi- 

 bians, and some Ganoids, serves 

 as the urinogenital duct. 



Functions exclusively as the 

 duct of the mesonephros, i.e., 

 the urinary duct. 



In Elasmobranchs it degene- 

 rates in post-embryonic life, 

 vestiges of its proximal portion 

 being retained. Its existence 

 in most other Fislies is doubt- 

 j ful. In Dipnoi and Amphibia it 

 is retained, at any rate for some 

 time, for its whole length, in a 

 fuuctionless and often but little 

 degenerate condition. 



When present, becomes 

 whole genital duct. 



the 



Probaljl V unrepresented (comp 

 35-2). 



The proximal end becomes the 

 rete and vasa efferentia testis, 

 the caput epididymis, and per- 

 haps also the stalked hydatid 

 of Morgagni : the distal end be- 

 comes the paradidymis (Griralde's 

 organ). 



The greater part of the proxi- 

 mal portion becomes the par- 

 ovarium, the distal the paroo- 

 phoron. 



The proximal portion becomes 

 the corpus and cauda epidymis 

 and the distal the seminal duct 

 (vas deferens). 



The greater part, as a rule, 

 degenerates ; the proximal por- 

 tion maybe retained in a vestigial 

 form in the region of the par- 

 ovarium. In certain cases it 

 may persist, as a whole, as 

 Gartner's canal. The distal end 

 becomes the organ of Weber. 



The proximal portion becomes 

 the unstalked hydatid of Slor- 

 gagni, the distal, in some Mam- 

 mals, the so-called ' ' uterus 

 maseulinus." In exceptional 

 cases the whole is retained as 

 Raihke's duct. In Sauropsida 

 the distal part usually dis- 

 appears. 



Becomes 

 duct. 



the whole genital 



Appears to arise in part (ure- 

 ter) from the distal end of the 

 mesonephric duct, and in part 

 (secreting elements) as a caudal 

 extension of the mesonephros. 



